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Title: Diffusive dynamics during the high-to-low density transition in amorphous ice

Water exists in high- and low-density amorphous ice forms (HDA and LDA), which could correspond to the glassy states of high- (HDL) and low-density liquid (LDL) in the metastable part of the phase diagram. However, the nature of both the glass transition and the high-to-low-density transition are debated and new experimental evidence is needed. Here we combine wide-angle X-ray scattering (WAXS) with X-ray photon-correlation spectroscopy (XPCS) in the small-angle X-ray scattering (SAXS) geometry to probe both the structural and dynamical properties during the high-to-low-density transition in amorphous ice at 1 bar. By analyzing the structure factor and the radial distribution function, the coexistence of two structurally distinct domains is observed at T = 125 K. XPCS probes the dynamics in momentum space, which in the SAXS geometry reflects structural relaxation on the nanometer length scale. The dynamics of HDA are characterized by a slow component with a large time constant, arising from viscoelastic relaxation and stress release from nanometer-sized heterogeneities. Above 110 K a faster, strongly temperature-dependent component appears, with momentum transfer dependence pointing toward nanoscale diffusion. This dynamical component slows down after transition into the low-density form at 130 K, but remains diffusive. In conclusion, the diffusive character ofmore » both the high- and low-density forms is discussed among different interpretations and the results are most consistent with the hypothesis of a liquid–liquid transition in the ultraviscous regime.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [5] ;  [2] ;  [2] ;  [1] ;  [2] ;  [2] ;  [4] ;  [6] ;  [6] ;  [7] ; ORCiD logo [6] ;  [3] ;  [2] ;  [2]
  1. Stockholm Univ., Stockholm (Sweden); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  2. Stockholm Univ., Stockholm (Sweden)
  3. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Hamburg Centre for Ultrafast Imaging, Hamburg (Germany)
  4. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
  5. KTH Royal Institute of Technology, Stockholm (Sweden)
  6. Univ. of Innsbruck, Innsbruck (Austria)
  7. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-76SF00515; 667205; 2013-3737-VR; P2ZHP2 148666; I1392; EXC1074; AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 114; Journal Issue: 31; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; liquid–liquid transition; glass transition; amorphous ice; X-ray photon-correlation spectroscopy; supercooled water
OSTI Identifier:
1390292
Alternate Identifier(s):
OSTI ID: 1393142